1. Field of the Invention
The present invention relates to techniques for determining power consumption for a set of computer systems. More specifically, the present invention relates to a method and apparatus for generating a dynamic power-flux map for a set of computer systems.
2. Related Art
Large businesses often maintain datacenters containing dozens or even hundreds of servers that provide various computational services. Since excessive heat can cause premature failure of components within servers, providing sufficient cooling capacity to remove the heat generated by these servers is a primary concern for operators of these datacenters.
At the present moment, large datacenters typically over-provision cooling capacity. More specifically, large datacenters provision cooling capacity by adding up the faceplate power ratings for each server in the datacenter and then providing sufficient cooling capacity to meet this estimated maximum level of power consumption. Typically, the faceplate power rating is higher than it is possible to achieve because the faceplate power ratings are extremely conservative estimates of the maximum theoretically possible power consumption of the individual components and the field-replaceable units (FRUs) within a server.
Note that the faceplate power rating is typically determined by adding up the power rating of each individual component and each FRU within the server. Therefore, the conservatively-high power rating estimates for these individual components and FRUs are reflected in the faceplate power rating.
Furthermore, average server utilization factors are low. As a result, datacenters are being designed to provide an amount of cooling capacity that matches a maximum theoretically possible power consumption, even though the actual cooling requirements may never exceed half of this maximum cooling capacity. Thus, it is desirable to more accurately measure the dynamic power consumption of servers to prevent needless and expensive over-provisioning of cooling systems for the servers.
One technique for measuring the dynamic power consumption of a server is to place a hardware power monitor between an external power supply and the server. Unfortunately, a hardware power monitor is expensive, typically costing many thousands of dollars. Furthermore, a hardware power monitor only measures the total power entering the server and hence cannot report on the power consumption of the individual components within the server.
A related challenge for datacenter operators is to balance the power flux and the temperature across a datacenter. Large disparities between “hot” and “cold” zones within a datacenter can result in cooling inefficiencies, which can significantly increase datacenter electricity costs. Furthermore, local “hot spots,” caused by an aggregation of computer systems or racks, can lead to poor long-term reliability of the computer systems located within the local hot spot. A power-flux density map can be used to determine how to provision cooling within the datacenter and can be used to determine where to place computer systems within the datacenter to substantially balance the power flux across a datacenter. Note that a power-flux map plots power-flux density, typically expressed as a power density in kilowatts per square foot, against the physical position of the computer systems within the datacenter. Unfortunately, present techniques for generating a power-flux map for a datacenter are time-consuming and expensive.
One approach used by datacenter operators to generate a power-flux map is to use Computation Fluid Dynamics (CFD) techniques to assess the spatial heat distribution in the data center. Under these techniques, temperature sensors are placed throughout the datacenter to collect thermal data, which is then used in CFD computations to infer spatial thermal-flux densities. Note that only measuring the temperature is not sufficient because it does not account for the rate of cool air being vented into the room. For example, if a temperature sensor is placed near a cool air vent, the temperature in that area would be lower than a temperature sensor placed near a rack of servers. Hence, a CFD analysis can be used to account for the airflow characteristics within the datacenter. Note that the airflow characteristics can also include the airflow through the racks and the computer systems (i.e., the change in temperature of the air flowing through the computer system).
Unfortunately, this technique requires manually taking temperature measurements within the datacenter and the use of complex CFD analysis, which is time-consuming and expensive. Furthermore, a CFD analysis is a one-time snapshot of the power flux within the datacenter. This power-flux mapping can quickly become out-of-date if the load profiles of the computer systems within the datacenter change, or when computer systems are upgraded or reconfigured.
Another approach for generating a power-flux map uses a robot that travels along each aisle of the datacenter taking temperature measurements using a temperature sensor. The temperature data collected by the robot is then entered into complex CFD software that infers the thermal flux within the datacenter. Although the robot can be configured to automatically travel along each aisle to collect temperature readings, this technique still requires the use of complex CFD analysis and further requires an expensive robot.
Hence, what is needed is a method and an apparatus for generating a power-flux map within a datacenter without the problems described above.